# Angle of a semicircle on a ramp

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1. Nov 20, 2015

### stewood

1. The problem statement, all variables and given/known data
The semicylinder of mass m and radius r lies on the rough inclined plane for which ϕ = 10∘ and the coefficient of static friction is μs = 0.3. Determine if the semicylinder slides down the plane, and if not, find the angle of tip θ of its base AB
2. Relevant equations
f=uN

3. The attempt at a solution
I think this requires some weird trigonemetry... I already calculated that the cylinder does not slide down but I cannot calculate the angle of theta

2. Nov 20, 2015

### Staff: Mentor

What did you try so far?
What do you know about equilibrium positions?

3. Nov 20, 2015

### haruspex

Your drawing of the forces could be a little more accurate. Where will the line of action of the normal force intersect AB?

4. Nov 22, 2015

### stewood

I've tried a few different triangles, but I cant figure it out. I know nothing about equilibrium positions.

5. Nov 22, 2015

### stewood

How can I calculate that?

6. Nov 22, 2015

### stewood

Never mind, I figured it out. In case your curious you use the law of sines...